Embolic protection device

ABSTRACT

Embolic protection devices useful for filtering emboli during interventional cardiac, vascular, or other procedures are described. The device can include first and second expandable mesh filters having open and closed ends. The first filter is attached to a catheter at its closed end. The second filter is attached to a steerable guide wire at its closed end. The second filter includes a cinching wire circumferentially attached to the filter. The filters are deployed in separate vessels, such as the brachiocephalic artery and the left common carotid artery. A procedure is performed, and the filters trap any emboli travelling through the path of the filters. At the end of the procedure, the second filter is closed using the cinching wire, and retracted into the first filter. Both the first and second filters are collapsed into a sheath and removed from the body with along with any emboli trapped in the filters.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No.13/782,657, filed Mar. 1, 2013, the disclosure of which is herebyincorporated by reference herein.

BACKGROUND OF THE DISCLOSURE

The present disclosure is related to protecting against embolism, andmore particularly to devices, systems, and methods for the filtrationand removal of debris within blood vessels.

Arterial embolism is a sudden interruption of blood flow to an organ orbody part due to an embolus, e.g., debris or a clot. During a surgicalintervention, such as a cardiac intervention, a vascular intervention,or a coronary intervention, tissue, plaque, and/or other masses may bedislodged due to the intervention, resulting in an embolus. These emboliare capable of traveling far from their origins, migrating to othersites of the vasculature and resulting in potentially life threateningcomplications. For example, an embolus may travel through the carotidartery and inhibit the flow of blood to the brain, which may result inthe death of brain cells, i.e., cause a stroke. A blockage of thecarotid arteries is the most common cause of a stroke.

BRIEF SUMMARY OF THE DISCLOSURE

In one embodiment according to the present disclosure, an embolicprotection device includes a first filter having an open end and aclosed end, the closed end being connected to a tube having a conduit.The device also includes a second filter having an open end and a closedend. The second filter is connected to a first wire, and the first wireextends into the conduit of the tube. A second wire has a first portionand a second portion. The first portion of the second wire iscircumferentially attached to the open end of the second filter, and thesecond portion of the second wire extends into the conduit of the tube.

In another embodiment according to the present disclosure, a method ofproviding embolic protection to a patient includes the steps ofdelivering a sheath into a first blood vessel of the patient, the sheathhousing a first filter and a second filter, deploying the first filterin the first blood vessel with a first guide structure, and deployingthe second filter in a second blood vessel with a second guidestructure. An additional step includes cinching an open end of thesecond filter with a cinching wire attached to the open end of thesecond filter.

In another embodiment according to the present disclosure, an embolicprotection device includes a first filter having a closed proximal endand an open distal end, the closed proximal end having a conical shapeand the open distal end having a cylindrical shape. The device alsoincludes a second filter having an open proximal end and a closed distalend, the open proximal end having a cylindrical shape and the closeddistal end having a conical shape. The device additionally includes acatheter having a proximal end, a distal end, and a lumen extendingtherebetween, the distal end of the catheter being fixed to the closedproximal end of the first filter. The device includes a steerable guidewire having a proximal end and a distal end, the distal end of thesteerable guide wire being fixed to the closed distal end of the secondfilter. The device further includes a cinching wire having a firstportion and a second portion, the first portion of the cinching wirebeing circumferentially attached to the open proximal end of the secondfilter. The steerable guide wire and the second portion of the cinchingwire extend through the open distal end of the first filter and furtherthrough the lumen of the catheter.

In still a further embodiment according to the present disclosure, anembolic protection device includes a first filter and a second filter,each filter having an open end and a closed end defining an interiorregion therebetween. The device includes a catheter coupled to theclosed end of the first filter. A first wire extends through a portionof the catheter and the interior regions of the first and secondfilters, and has an end attached to the closed end of the second filter.The second filter is configured to be at least partially received withinthe interior region of the first filter by manipulation of the firstwire.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a schematic view of the aorta.

FIG. 2 illustrates a schematic view of a proximal basket of an embolicprotection device being introduced into the aorta.

FIG. 3 illustrates a schematic view of a distal basket of the embolicprotection device of FIG. 2 being deployed into the left common carotidartery.

FIG. 4 illustrates a sectional side view of the embolic protectiondevice of FIGS. 2-3 including the distal basket and the proximal basketaccording to an embodiment of the present disclosure.

FIG. 5 illustrates a side view of the embolic protection device of FIG.4.

FIG. 6 illustrates a sectional side view of the embolic protectiondevice of FIG. 4 with the distal basket cinched and being retracted intothe proximal basket.

FIG. 7 illustrates a side view of the embolic protection device of FIG.4 with the distal basket retracted into the proximal basket.

FIG. 8 illustrates a vertical sectional view of an inner mold used toproduce a filter for an embolic protection device according to anembodiment of the present disclosure.

FIG. 9 illustrates a schematic view of the positioning of struts in afilter of an embolic protection device according to an embodiment of thepresent disclosure.

FIG. 10 illustrates a horizontal sectional view of an alternateembodiment of an inner mold used to produce a filter for an embolicprotection device according to an embodiment of the present disclosure.

FIG. 11 illustrates a vertical sectional view of an outer mold used toproduce a filter for an embolic protection device according to anembodiment of the present disclosure.

FIG. 12 illustrates a vertical sectional view of an alternate embodimentof an outer mold used to produce a filter for an embolic protectiondevice according to an embodiment of the present disclosure.

FIG. 13 illustrates a side view of a clam shell used to produce a filterfor an embolic protection device according to an embodiment of thepresent disclosure.

FIG. 14 illustrates a top view of the clam shell of FIG. 13.

DETAILED DESCRIPTION

A continuing need exists for devices and systems that inhibit embolifrom traveling to parts of a patient's vasculature where they may blockblood flow to critical organs and threaten the life of the patient.

Particular embodiments of the present disclosure are described withreference to the accompanying drawings. In the figures and in thedescription that follow, like reference numerals identify similar oridentical elements. As shown in the drawings and as described throughoutthe following description, the term “proximal” refers to the end of thedevice that is closer to the user and the term “distal” refers to theend of the device that is farther from the user.

FIG. 1 illustrates aorta 100, the largest artery in the body,originating from the left ventricle (not shown) and extending down tothe abdomen. Blood flows as indicated by arrow “A” from the leftventricle, through the aortic valve (not shown), through ascending aorta112 to aortic arch 110. Three major arteries branch from aortic arch110. Brachiocephalic artery 106 branches into right subclavian artery107, supplying blood to the right arm, and right common carotid artery109, supplying blood to the head and neck. Left common carotid artery104 supplies blood to the head and neck. Left subclavian artery 102supplies blood to the left arm. Blood from ascending aorta 112 notpassing through one of these three arteries continues down descendingaorta 108 as shown by arrow “B”. Variations of the anatomy illustratedin FIG. 1 are possible and sometimes are relatively common. For example,about 10% of the population has a common brachiocephalic trunk, in whichboth common carotid arteries 104, 109 and right subclavian artery 107arise from a single trunk off aortic arch 110. During interventionalsurgical, cardiac, and/or vascular procedures, there is a risk thatemboli may break free and travel up ascending artery 112 and cause ablockage of brachiocephalic artery 106, right common carotid artery 109,and/or left common carotid artery 104, causing reduced blood flow to thebrain and possibly a stroke. Devices and methods described herein may beused during interventional procedures to capture and remove emboli fromthe body.

Referring to FIG. 2, in one embodiment, embolic protection device 150includes a first filter in the nature of proximal basket 200. Proximalbasket 200 is a collapsible/expandable mesh basket with pores that arelarge enough to allow for the passage of blood, but small enough to trapemboli passing into proximal basket 200.

Embolic protection device 150, attached to the distal end of catheter230 (shown in FIG. 4), is introduced into or near the ostium of a bloodvessel, such as brachiocephalic artery 106 of aortic arch 110, viaintroducer sheath 270. Introducer sheath 270 may be initially introducedinto the femoral artery, subclavian artery, or other vessel as is knownin the art. During introduction, proximal basket 200 is in a collapsedstate within introducer sheath 270. Once introducer sheath 270 is placednear the ostium of brachiocephalic artery 106, catheter 230 is pusheddistally until proximal basket 200 exits the confines of introducersheath 270. For embodiments in which proximal basket 200 is acollapsible/expandable mesh basket, proximal basket 200 willautomatically open to its expanded configuration as seen in FIG. 2. Theexpansion is such that substantially all the blood flowing throughbrachiocephalic artery 106 passes through proximal basket 200.

Now referring to FIG. 3, once proximal basket 200 is expanded inbrachiocephalic artery 106, a second filter, in the nature of distalbasket 210, is then deployed. Distal basket 210 is connected tosteerable guidewire 220 which extends through proximal basket 200 andinto catheter 230 (shown in FIG. 4). Distal basket 210 may also take theform of a collapsible/expandable mesh basket with pores that are largeenough to allow for the passage of blood, but small enough to trapemboli passing into distal basket 210. Prior to deployment, for exampleduring introduction into the body, distal basket 210 may be collapsedwithin proximal basket 200, which itself is in a collapsedconfiguration. During deployment, distal basket 210 may automaticallyopen to its expanded configuration once pushed distally out of proximalbasket 200 via steerable guidewire 220. In its expanded configuration,distal basket 210 can be directed to or near the ostium of a nearbyvessel, such as left common carotid artery 104, using steerableguidewire 220.

With both baskets 200, 210 expanded in the desired blood vessel, acardiac or vascular intervention or other procedure can be performed.Such a cardiac or vascular intervention or other procedure may dislodgeor otherwise result in emboli moving through the blood. If an embolustravels into the path of the expanded proximal basket 200 or distalbasket 210, the embolus will become trapped in the mesh of therespective basket. Baskets 200, 210 remain in the expanded configurationfor the duration of the cardiac or vascular interventional procedure.Once the interventional procedure is complete, distal basket 210 can becinched closed to trap any emboli therein. After cinching, distal basket210 is pulled into proximal basket 200, and both baskets 200, 210 andcatheter 230 are removed from the patient along with any emboli trappedduring the procedure. As catheter 230 and baskets 200, 210 pass backinto introducer sheath 270, baskets 200, 210 are forced into a collapsedconfiguration inside introducer sheath 270. The cinching and removalsteps are described more fully below with reference to FIGS. 6-7.

Referring now to FIG. 4, embolic protection device 150 shown in FIGS.2-3 is illustrated in further detail. Baskets 200, 210 each have acylindrically shaped open portion 202, 212, with a conically shapedclosed end portion 204, 214 respectively. Baskets 200, 210 are eachformed of a braided mesh structure supported by struts 240 (struts 240illustrated in FIG. 5).

For example, the mesh of baskets 200, 210 can be a braided superelasticmetal alloy such as nickel-titanium alloy of the type sold under thedesignation NITINOL. As one example, 32-strand NITINOL braid may beused. Alternately, or in addition, 72-strand or 144-strand NITINOL braidmay be used. A braid of approximately 0.0010-0.0015 inch (0.025-038 mm)diameter can be used for the mesh of baskets 200, 210.

Still referring to FIG. 4, distal basket 210 is coupled to steerableguidewire 220, which extends through proximal basket 200 and furtherthrough catheter 230. As illustrated in FIG. 4, closed end portion 204of proximal basket 200 faces the proximal end of embolic protectiondevice 150. Cylindrically shaped open portion 202 of proximal basket 200faces the distal end of embolic protection device 150. Distal basket 210is generally in line with proximal basket 200 by virtue of steerableguidewire 220, but in the opposite orientation. As such, cylindricallyshaped open portion 212 of distal basket 210 faces the proximal end ofembolic protection device 150, and closed end portion 214 faces thedistal end of embolic protection device 150.

The shape of proximal basket 200 and distal basket 210 is maintained byvirtue of the shape-maintaining material forming the baskets 200, 210.For example, NITINOL can be heat set to a particular shape, such as thegenerally cylindrical and/or conical shapes described above withreference to baskets 200, 210. The process of heat setting is describedin greater detail below with reference to FIGS. 8-14. Baskets 200, 210are also elastic such that they each may be radially collapsed into acollapsed configuration. The collapsed configuration may be particularlyuseful for creating a low profile of baskets 200, 210, such that theymay be delivered into the body in an introducer sheath 270 in the lowprofile collapsed condition. The shape memory of baskets 200, 210 helpsensure that, upon a reduction of compressive forces, baskets 200, 210automatically radially expand from the low profile, collapsed conditioninto the expanded configuration. The shape taken in the expandedconfiguration is dictated by the shape in which the material was heatset.

The distal end of steerable guidewire 220 is connected to end screw 250of distal basket 210. End screw 250 is internally threaded tothreadingly engage with external threads on the distal end of steerableguidewire 220. Other mating configurations are also possible, forexample external threading on end screw 250 and internal threading onsteerable guidewire 220. Steerable guidewire 220 extends distally fromend screw 250 through an approximate midline of proximal basket 200.Steerable guidewire 220, having an outer diameter smaller than the innerdiameter of catheter 230, extends further distally through anapproximate midline of catheter 230. The proximal end of the steerableguidewire 220 can extend to a proximal end of the system (not shown)where a user is able to steer guidewire 220, and in turn, steer distalbasket 210. Steerable guidewire 220 may, for example, include a pullableguidewire having at least one relatively stiff portion and onerelatively flexible portion for positioning distal basket 210. Steerableguidewire 220 may include a pushable guidewire to which tension may beapplied to steer distal basket 210 into the desired location. Mechanismsfor steerable guidewires are known in the art and not described furtherherein.

The proximal end of proximal basket 200 is coupled to hypotube 260,which, in turn, is coupled to the distal end of catheter 230. Hypotube260 may be formed as an integral part of catheter 230 or may beseparately attached, such as with adhesives or through welding. Theouter diameter of catheter 230 is small enough to pass through the innerdiameter of introducer sheath 270. For example, the catheter 230 may bebetween about 3-15 French, 4-12 French, 5-8 French, or approximately 6-7French.

Still referring to FIG. 4, elongated cinch wire 280 (shown as a brokenline), which may for example be a suture or other suitable cable-typematerial, extends generally around the circumference of cylindricalportion 212 of distal basket 210 and back through proximal basket 200and catheter 230. Cinch wire 280 may, for example, weave in and out ofthe mesh structure of distal basket 210 in a purse string configuration.Cinch wire 280 may additionally or alternately attach circumferentiallyto two or more struts 240 (described in more detail below with referenceto FIG. 5) in distal basket 210. Cinch wire 280 extends through thecatheter 230 to a proximal end (not shown) where the user is able tocontrol cinch wire 280, for example, with a pulling motion. Pullingcinch wire 280 proximally causes distal basket 210 to constrict at thepoint of attachment, much like pulling a purse string. This functions tofurther secure emboli trapped in distal basket 210, described in moredetail below with reference to FIGS. 6-7.

Now referring to FIG. 5, the mesh of baskets 200, 210 can bestructurally reinforced with struts 240, such as solid, elongated piecesof superelastic metal alloy, such as NITINOL. In one example, each strut240 is between about 0.005-0.015 inches (0.127-0.381 mm) orapproximately 0.010 inches (0.254 mm) in diameter. Each strut 240 isabout ten times as thick as the mesh braid and aids baskets 200, 210 inmaintaining the generally cylindrical shape of open portions 202, 212.By helping to maintain the generally cylindrical shape of open portions202, 212, struts 240 also help ensure that baskets 200, 210 maintaincontact with the walls of vessels in which they are deployed. Referringback to FIG. 3, for example, struts 240 help proximal basket 200maintain contact with the walls of brachiocephalic artery 106.Similarly, struts 240 help distal basket 210 maintain contact with thewalls of left common carotid artery 104. This contact of baskets 200,210 to the walls of the blood vessels increases the likelihood oftrapping emboli that pass into the blood vessels.

Now referring back to FIG. 5, each basket 200, 210 can have one or morestruts 240 and the exact number of struts in each basket 200, 210 islargely a matter of design choice. Generally, more struts 240 in abasket results in an improved ability of the mesh to maintain itscylindrical shape when in the expanded condition. However, more struts240 in a basket results in an increased profile of the basket when thebasket is in the collapsed configuration. Therefore the specific numberand design of struts 240 in proximal basket 200 and distal basket 210depends on the materials used, the particular application of the device,and the desired performance of the device.

Generally, struts 240 in proximal basket 200 are spaced equally aroundcylindrically shaped portion 202. For example, three struts would beplaced 120° apart, four struts would be placed 90° apart, etc. Eachstrut 240 begins distal to the distal end of cylindrically shaped openportion 202 of proximal basket 200. Struts 240 extend proximally,generally parallel to, and along the surface of, cylindrically shapedopen portion 202. Struts 240 follow the surface of proximal basket 200and curve toward conical closed end portion 204. All struts 240 inproximal basket 200 meet at conical closed end portion 204. Thestructure of struts 240 in distal basket 210 is similar, with thedirectionality being reversed. In other words, struts 240 of distalbasket 210 extend past the mesh of distal basket 210 in the proximaldirection, and each meet at the proximal conical closed end portion 214.

In the embodiment illustrated in FIG. 5, proximal basket 200 includesthree struts 240 while distal basket 210 includes four struts. As willbecome clear below, the ability of distal basket 210 to achieve a smallprofile is one design factor. As such, in an embodiment, distal basket210 has fewer struts 240 than proximal basket 200, such as three strutsin distal basket 210 and four struts in proximal basket 200. The processfor manufacturing baskets 200, 210, including struts 240, is describedin more detail below with reference to FIGS. 8-10.

Now referring to FIG. 6, distal basket 210 is illustrated cinched closedand being retracted into proximal basket 200. After insertion of embolicprotection device 150 and completion of a surgical intervention, embolicprotection device 150 is extracted from the patient. Prior toextraction, distal basket 210 is retracted proximally into proximalbasket 200. Prior to the retraction step, distal basket 210 is cinchedclosed to reduce the likelihood of emboli escaping distal basket 210 andre-entering the blood stream. As described above with reference to FIG.4, pulling cinch wire 280 causes distal basket 210 to constrict likepulling a purse string. In an embodiment, the pulling force required tocinch distal basket 210 closed is minimal and does not substantiallycause movement of distal basket 210 proximally toward proximal basket200.

The constricting action allows distal basket 210, with any trappedemboli therein, to be fully or nearly fully sealed before attempting toretract distal basket 210 into proximal basket 200. Any agitation ofbaskets 200, 210 may increase the likelihood of a trapped embolusescaping back into the blood stream. Such agitation may occur whenretracting distal basket 210 into proximal basket 200. By fully, ornearly fully, sealing open portion 212 of distal basket 210 with cinchwire 280 prior to retraction, the likelihood of an embolus trappedwithin distal basket 210 inadvertently re-entering the blood streamduring retraction is significantly reduced.

In other words, prior to cinching, distal basket 210 is in the expandedconfiguration, with open end 212 having a pre-cinched diameter. Thecinching action collapses open end 212 of distal basket 210 to asmaller, post-cinched diameter. This is possible due to theexpandable/collapsible nature of distal basket 210. Even when openportion 212 is collapsed due to the cinching action, the rest of distalbasket 210 remains in a generally expanded configuration. Thepost-cinched diameter of open portion 212 is smaller than the diameterof open portion 202 of proximal basket 200 when proximal basket 200 isin the expanded configuration. These relative diameters help ensure thatopen portion 212 of distal basket 210 can be retracted into open portion202 of proximal basket 200 after being cinched.

Now referring to FIG. 7, distal basket 210 is illustrated retracted intoproximal basket 200. The user may accomplish this by pulling steerableguidewire 220 proximally until open end 212 of distal basket 210 isproximal of open end 202 of proximal basket 200. In this configuration,distal basket 210 and proximal basket 200 form a fully or nearly fullysealed filter unit. Distal basket 210 and proximal basket 200 can beconsidered a sealed filter unit in this configuration because distalbasket 210 partially or fully occupies open cylindrical portion 202 ofproximal basket 200. During extraction of embolic protection device 150,both distal basket 210 and proximal basket 200 are radially collapsedand removed through introducer sheath 270, as described above withreference to FIG. 4. These movements may agitate emboli trapped withinproximal basket 200 or distal basket 210. However, because distal basket210 is located partially within proximal basket 200 during thecollapsing action as a sealed filter unit, agitated emboli are unlikelyto escape back into the blood stream. As proximal basket 200 and distalbasket 210 proximally pass through introducer sheath 270, baskets 200,210 radially collapse into introducer sheath 270. Once in the collapsedconfiguration, both baskets 200, 210 can be extracted from the patient,with any emboli trapped during the interventional procedure securelyremaining within the confines of the collapsed baskets 200, 210throughout extraction.

Turning now generally to FIGS. 8-14, devices useful for themanufacturing of proximal and distal baskets 200, 210 are shown. Toproduce proximal and/or distal baskets 200, 210, tubular braided mesh242 (illustrated in FIG. 9) is fitted over inner mold 300, as seen inFIG. 8. Inner mold 300 provides a structure upon which proximal basket200 or distal basket 210 may be formed. Inner mold 300 can be formedfrom a range of materials that withstand heating, are commonlyavailable, are durable and have good heat transfer properties. Forexample, brass or similar materials can be used for the inner mold 300.In the illustrated embodiment, inner mold 300 resembles the shape ofproximal and distal baskets 200, 210, having generally cylindricalportion 305 and conical portion 310. The interior of cylindrical portion305 can include hollow portion 315. Hollow portion 315 may reduce themass of inner mold 300 and reduce the time necessary for any heating orcooling of inner mold 300.

The dimensions of inner mold 300 can be varied for baskets of differentsizes. For example, the following dimensions of inner mold 300 may beuseful for forming proximal basket 200. Height H₁ of cylinder portion305 is between about 1-2 inches (25.4-50.8 mm) or approximately 1.5inches (38.1 mm). Height H₂ of conical portion 310 is between about0.5-1.1 inches (12.7-27.94 mm) or approximately 0.8 inches (20.32 mm).Diameter D₁ of hollow portion 315 is between about 0.25-0.75 inches(6.35-19.05 mm) or approximately 0.5 inches (12.7 mm). Diameter D₂ ofcylindrical portion 305 is between about 0.5-1 inches (12.7-25.4 mm) orapproximately 0.748 inches (19 mm). Angle α of conical portion 310 isbetween about 15°-25°, or approximately 20°.

Inner mold 300 with a similar shape but different dimensions can be usedfor distal basket 210. For example, the following dimensions of innermold 300 may be useful for forming distal basket 210. Height H₁ ofcylinder portion 305 is between about 1-2 inches (25.4-50.8 mm) orapproximately 1.5 inches (38.1 mm). Height H₂ of conical portion 310 isbetween about 0.25-0.75 inches (6.35-19.05 mm) or approximately 0.5inches (12.7 mm). Diameter D₁ of hollow portion 315 is between about0.25-0.75 inches (6.35-19.05 mm) or approximately 0.5 inches (12.7 mm).Diameter D₂ of cylindrical portion 305 is between about 0.5-1 inches(12.7-25.4 mm) or approximately 0.787 inches (20 mm). Angle α of conicalportion 310 is between about 25°-35°, or approximately 30°.

The provided dimensions are merely illustrative and are in no way meantto limit the scope of the disclosure. These dimensions can be varied fordifferent preferences or applications. For example, in one embodiment,inner mold 300 used to form proximal basket 200 has a larger diameter D₂of cylindrical portion 305 than inner mold 300 used to form distalbasket 210. In this embodiment, the larger diameter D₂ of proximalbasket 200 inner mold 300 results in a larger diameter of proximalbasket 200. This configuration may make it easier to retract distalbasket 210 into proximal basket 200, described above in relation to FIG.7.

Once tubular braided mesh 242 is on inner mold 300, struts 240 areinserted between the mesh and inner mold 300 in the desiredconfiguration. Struts 240 may be equally spaced. For example, in abasket with four struts 240, the struts may be placed every 90°, whereasin a basket with three struts, the struts may be placed every 120°. Thenumber and exact spacing of struts 240, however, is largely a matter ofdesign choice as discussed in detail above.

Referring now to FIG. 9, placement of two struts 240 a, 240 b withinbraided mesh 242 is illustrated. Inner mold 300 is omitted from FIG. 9for clarity of illustration. Each strut 240 a, 240 b is initially placedbetween braided mesh 242 and cylindrical portion 305 of inner mold 300.Struts 240 a, 240 b are advanced toward conical portion 310 of innermold, and are passed through the mesh near the angled transition ofinner mold 300 from cylindrical portion 305 to conical portion 310.Struts 240 a, 240 b are then woven back inside the mesh and guidedtoward the tip of conical portion 310.

To aid in the introduction and weaving of struts 240, the outer surfaceof cylindrical portion 305 of inner mold 300 can include a plurality ofnotches or grooves 320 running the length of cylindrical portion 305. Asshown in FIG. 10, grooves 320 aid in inserting struts 240 betweenbraided mesh 242 and inner mold 300, especially if braided mesh 242 istightly fitted over inner mold 300.

For proximal basket 200, after guiding struts 240 toward the tip of theconical portion 310, struts 240 are situated on or near the outersurface of a cylindrical structure, such as hypotube 260 (illustrated inFIGS. 5-6). Hypotube 260 can be between about 0.125-0.375 inches long(3.175-9.525 mm), or approximately 0.25 inches long (6.35 mm). Hypotube260 is between about 10-15 gauge, or approximately 13 gauge. Struts 240are then cinched to hypotube 260 by a marker band (not illustrated).Marker bands are known in the art and can be formed of, for example, aradiopaque material such as platinum iridium that allows forvisualization inside the body. Struts 240, the marker band and hypotube260 are joined together, such as by adhesives, soldering, brazing, orlaser welding to remove any excess material.

For distal basket 210, after guiding struts 240 toward the tip ofconical portion 310 of inner mold 300, struts 240 are joined with thebraid atop of end screw 250 (shown in FIG. 4) and cinched using a markerband. Struts 240, the marker band and end screw 250 are joined together,such as by adhesives, soldering, brazing, or laser welding to remove anyexcess material.

Now referring to FIG. 11, outer mold 325 is illustrated. After weldingproximal basket 200, outer mold 325 is placed over the conical portion310 of the inner mold, sandwiching braided mesh 242 therebetween. Outermold 325 includes cylindrical portion 330 and hollow conical portion 335within cylindrical portion 330. Hollow conical portion 335 is generallydimensioned to correspond to conical portion 310 of inner mold 300.Outer mold 325 can also include hollow conduit 340 connecting the tip ofhollow conical portion 335 to the outside of outer mold 325. Hollowconduit 340 is dimensioned to accept hypotube 260 and other elementsextending from the tip of conical portion 204 of proximal basket 200.

Outer mold 325, which can be used while forming proximal basket 200, canbe a variety of sizes depending on the desired size of proximal basket200. In one embodiment, height H₃ of outer mold 325 is between about 1-2inches (25.4-50.8 mm) or approximately 1.5 inches (38.1 mm). Height H₄of hollow conical portion 335 is between about 0.5-1.1 inches(12.7-27.94 mm) or approximately 0.8 inches (20.32 mm). Diameter D₃ ofouter mold 325 is between about 0.5-1.0 inches (12.7-25.4 mm) orapproximately 0.748 inches (19 mm). Diameter D₄ of hollow conduit 340 isbetween about 0.125 inches and 0.25 inches (3.175-6.35 mm) orapproximately 0.1875 inches (4.76 mm). As with inner mold 300, outermold 325 may be formed from a range of materials that withstand heating,are commonly available, are durable and have good heat transferproperties. For example, brass or similar materials can be used forouter mold 325.

Now referring to FIG. 12, outer mold 350 is illustrated. After weldingdistal basket 210, outer mold 350 is placed over conical portion 310 ofinner mold 300, sandwiching braided mesh 242 therebetween. Outer mold350 includes cylindrical portion 355 and hollow conical portion 360within cylindrical portion 355. Hollow conical portion 360 is generallydimensioned to correspond to conical portion 310 of inner mold 300.

Outer mold 350, which can be used while forming distal basket 210, canbe a variety of sizes depending on the desired size of distal basket210. In one embodiment, height H₅ of outer mold 350 is between about 1-2inches (25.4-50.8 mm) or approximately 1.5 inches (38.1 mm). Height H₆of the hollow conical portion 360 is between about 0.25-0.75 inches(6.35-19.05 mm) or approximately 0.5 inches (12.7 mm). Diameter D₅ ofouter mold 350 is between about 0.5-1 inches (12.7-25.4 mm) orapproximately 0.787 inches (20 mm). As with inner mold 300, outer mold350 may be formed from a range of materials that withstand heating, arecommonly available, are durable and have good heat transfer properties.For example, brass or similar materials can be used for outer mold 350.

Referring to FIGS. 13-14, clam shell 375 is illustrated in side and topviews, respectively. A pair of clam shells 375 (only one clam shellillustrated in FIGS. 13-14) may be used in conjunction with inner mold300, as well as either outer mold 325 or outer mold 350, to sandwichbraided mesh 242 into the desired configuration. Each clam shell 375approximates a hollow half-cylinder, generally corresponding to theshape of cylindrical portion 305 of inner mold 300. Two clam shells 375are each fitted over opposing sides of cylindrical portion 305 of innermold 300. Since each clam shell 375 approximates a hollow half cylinder,two clam shells 375 form an outer hollow cylinder that completelysurrounds and sandwiches cylindrical portion 305 of inner mold 300.

An embodiment of clam shell 375 that can be used with inner mold 300 mayhave height H₇ of between about 1-2 inches (25.4-50.8 mm) orapproximately 1.5 inches, (38.1 mm). Clam shell 375 may have thicknessT₁ of between about 0.075-0.175 inches (1.9-4.45 mm) or approximately0.125 inches (3.175 mm). If clam shell 375 is used to form proximalbasket 200, it may have diameter D₆ of between about 0.760-1.01 inches(19.3-25.65 mm). If clam shell 375 is used to form distal basket 210, itmay have diameter D₆ of between about 0.799-1.049 inches (20.29-26.64mm). As with inner mold 300, clam shells 375 may be formed from a rangeof materials that withstand heating, are commonly available, are durableand have good heat transfer properties. For example, brass or similarmaterials can be used for clam shells 375.

The clam shells 375 may be fitted onto cylindrical portion 305 of innermold 300 before, after, or at the same time that either outer mold 235(if forming proximal basket 200) or outer mold 350 (if forming distalbasket 210) is fitted onto conical portion 310 of inner mold 300. Outermold 325 or outer mold 350 may simply rest on top portions of clamshells 375, and need not attach to clam shells 375. As described abovewith reference to FIGS. 8 and 11-14, braided mesh 242 is fitted overinner mold 300 and surrounded on top by outer mold 325 (or outer mold350) and surrounded on the sides by two clam shells 375. Once braidedmesh 242 is sandwiched on all sides, it takes the shape of the moldsapplied. In this embodiment, the shape is a cylinder which is open onone side and which is conical on the other side.

When braided mesh 242 is a material that has shape memory, such asNITINOL, the sandwiched braid may be heated to set the desired shape.The assembly including inner mold 300, outer mold 325 (or outer mold350), clam shells 375 and sandwiched mesh with struts 240 is heated. Athermocouple lead may be used near the mesh to determine temperature ofthe mesh. The mesh is heated to between about 475°-575° C., orapproximately 530° C., to set the shape of the mesh. For different meshmaterials, and even for different compositions of NITINOL, differenttemperatures may be required for heat setting. Once set, the assembly iscooled, for example in an ambient water bath. Once cooled, clam shells375 and outer mold 325 (or outer mold 350) may be removed. The mesh maybe taken off inner mold 300, with the end product being proximal basket200 (if outer mold 325 was used) or distal basket 210 (if outer mold 350was used). Any excess mesh or struts 240 may be trimmed.

All provided dimensions, temperatures, angles, and materials are merelyillustrative and are in no way meant to limit the scope of thedisclosure. For example larger or smaller inner molds 300, outer molds325, 350 and clam shells 375 may be used for larger or smaller basketsto be used in larger or smaller vessels in the body.

Although the disclosure herein has been described with reference toparticular embodiments, it is to be understood that these embodimentsare merely illustrative of the principles and applications of thepresent disclosure. It is therefore to be understood that numerousmodifications may be made to the illustrative embodiments and that otherarrangements may be devised without departing from the spirit and scopeof the present disclosure.

1. A method of providing embolic protection to a patient comprising thesteps of: delivering a sheath into a first blood vessel of the patient,the sheath housing a first filter in a collapsed condition and a secondfilter in a collapsed condition; deploying the first filter in the firstblood vessel using a first guide member to transition the first filterto an expanded condition so that blood flows into an open end of thefirst filter; deploying the second filter in a second blood vessel usinga second guide member to transition the second filter to an uncinchedexpanded condition so that blood flows into an open end of the secondfilter; cinching the open end of the second filter with a cinch wireattached to the open end of the second filter to transition the secondfilter into a cinched expanded condition in which the open end of thesecond filter has a reduced diameter compared to the uncinched expandedcondition; and retracting the second guide member to pull the secondfilter in the cinched expanded condition at least partially into thefirst filter in the expanded condition.
 2. The method of claim 1,further comprising: retracting the first filter into the sheath whilethe second filter is at least partially within the first filter.
 3. Themethod of claim 2, further comprising: removing the first filter fromthe patient, wherein the second filter remains at least partially withinthe first filter during the removal of the first filter from thepatient.
 4. The method of claim 1, wherein during delivery of thesheath, the second filter is at least partially within the first filter.5. The method of claim 1, wherein the first filter and the second filtereach include a mesh structure.
 6. The method of claim 1, wherein thesecond filter includes a plurality of struts having free ends extendingbeyond the open end of the second filter.
 7. The method of claim 6,wherein cinching the open end of the second filter causes the free endsof the plurality of struts of the second filter to draw closer to oneanother in the cinched expanded condition of the second filter.
 8. Themethod of claim 7, wherein during the step of retracting the secondguide member, the free ends of the plurality of struts of the secondfilter guide the second filter into the first filter.
 9. The method ofclaim 6, wherein the plurality of struts of the second filter maintainthe open end of the second filter in a cylindrical shape in the expandedcondition of the second filter.
 10. The method of claim 9, wherein thefirst filter includes a plurality of struts with free ends extendingbeyond the open end of the first filter.
 11. The method of claim 10,wherein as the second filter is retracted into the first filter, thefree ends of the plurality of struts of the first filter are positionedradially outward of the second filter.
 12. The method of claim 1,wherein deploying the second filter includes translating the secondguide member with respect to the first filter.
 13. The method of claim12, wherein the second guide member extends through the first filter.14. The method of claim 1, wherein cinching the open end of the secondfilter includes pulling the cinch wire through the sheath.
 15. Themethod of claim 14, wherein the cinch wire extends through the firstfilter.
 16. The method of claim 14, wherein, upon pulling the cinchwire, the second filter remains in substantially the same translationalposition with respect to the first filter.
 17. The method of claim 14,wherein the second filter has a conical portion adjacent the open end ofthe second filter.
 18. The method of claim 17, wherein, as the cinchwire is pulled to transition the second filter from the uncinchedexpanded condition to the cinched expanded condition, the conicalportion of the second filter retains substantially the same shape. 19.The method of claim 1, wherein the reduced diameter of the open end ofthe second filter inhibits emboli trapped within the second filter fromexiting the second filter in the cinched expanded condition of thesecond filter.